The present invention relates to an improved air-suspension system for a vehicle, especially a closed or partly closed system.
An air-suspension system of the general type under consideration is described in DE 199 59 556 C1.
In such conventional air-suspension systems, a compressed-air delivery device such as a compressor is used, on the one hand, to pump air as needed from a compressed-air accumulator into the air-suspension bellows, and, on the other hand, to pump air as needed from the air-suspension bellows back into the compressed-air accumulator. To change over between these two compressed-air delivery directions, a changeover-valve device is provided between the compressed-air accumulator and air-suspension bellows on the one side and the compressed-air delivery device on the other side. In the air-suspension system described in DE 199 59 556 C1, the changeover-valve device can comprise, for example, two electrically actuatable 3/2-way valves designed as directly controlled solenoid valves.
In an air-suspension system, it is desired that the air-suspension bellows can be filled and emptied as rapidly as possible. This necessitates valve devices, and, in particular, also a changeover-valve device with large nominal width, or, in other words, with large passage cross section. Such valve devices have relatively large size and thus are relatively heavy and expensive.